In present world adequate amount of clean water supply is a challenging task due to contamination of surface water as well as ground water by synthetic chemicals like polychlorophenot, nitrophenols, thiophosphate pesticides, herbicides, textile azodyes and dibenzothiophenes which enter into environment from industrial effluents, domestic sewage and agriculture run off. To reduce the impact of environmental release of those pollutants and to increase water reusability oxidation chemistry plays a crucial role.
Catalyst fate is an important issue in both the economic and environmental performances of any new technology. However, designing metal complexes that activate H2O2O2 or O2 but are themselves inert to oxidation is the key to the synthesis of efficient transition metal oxidation catalysts. An approach pursued by researchers to achieve this goal has been to mimic enzymes that function as oxidation catalysts. Nature has evolved enzymes that are very efficient as oxidation catalysts. These include cytochrome P450 and peroxidases, enzymes that use an iron (IV) oxoporphyrin radical cation intermediate to catalyze the oxidation of various organic substrates selectively and efficiently. Though the enzymes that activate “Green” oxidants like O2 or H2O2 in aerobic biochemistry exhibit remarkable activity and selectivity, however, limits their technological applicability due to high costs, limited availability and less activity at extreme pH limit and ionic strength.
Macrocyclic ligands with various donor atoms are very important to stabilize metals with high valent oxidation states. Such macrocyclic complexes play a significant role in mimicking either structure and/or functions of several metallo enzymes, especially enzymes which use hydrogen peroxides or oxygen for their activity, Fe (III) complexes based on a class of tetraamidemacrocyclic ligands (Fe-TAML's) developed by Collins et. al. have several attributes that render them to be excellent functional mimics of peroxidases. In recent years various synthetic methods for TAML ligand has been reported.
References may be made to an article entitled ‘Catalase-Peroxidase Activity of Iron(III)-TAML Activators of Hydrogen Peroxide’ by Anindya Ghosh, Douglas A. Mitchell et. al in J. AM. CHEM. SOC. 2008, 130, 15116-15126 disclose FeIII-TAML Activators of Hydrogen Peroxide oxidation of a wide spectrum of targets including toxic polychlorophenols, thiophosphate pesticides and nitrophenols, azo dyes, dibenzothiophenes, an anthrax surrogate, and natural and synthetic estrogens.
 X1X2RaHHCH3bNO2HCH3cHHFdClClFMeOOCHCH3ClClCH3CH3HCH3CH3CH3CH3COOHHCH3
References may be made to U.S. Pat. No. 7,060,818 which relate to macrocyclic tetramido compounds and to a process for metal insertion. The complex is given below:

The tetra amido macrocyclic ligand is prepared by the process given below:

The diamide diamine intermediate is reacted with an activating diacid to form the macrocyclic tetramido compound having at least 11 atoms forming the macrocycle. Further, the said patent discloses the formation of LiFeB* as given below:

References may be made to an article titled “Nineteen-membered pentaazamacrocyclic complexes bearing tetraamide groups” by Nasman O. S. M. Baraka R. M et. al in Transition Metal Chemistry, Volume 22, Number 3, 1997, pp. 273-276(4) disclose a series of CoII, NiII, CuII and ZnII complexes incorporating pentaazamacrocyclic ligands via the template condensation of o-aminobenzoic acid with succinic or phthalic acids in the presence of diethylenetriamine. An article titled ‘Tetraamide Macrocyclic Complexes of Some Transition Metal Ions’ by Omar S. M. Nasman in Journal of Al Azhar University-Gaza (Natural Sciences), (2007), Vol. 9, page: 53-59 disclose a series of tetraazamacrocyclic complexes prepared by a process as shown in scheme below:

A series of tetraazamacrocyclic complexes bearing tetraamide groups is derived from o-aminobenzoic acid, with ethylene diamine or o-phenylene diamine and diethyl malonate in the presence of transition metal ions as templates. These complexes may be useful for investigation of metal containing—biological molecules such as metalloenzymes, and their catalytic activity for industry.
References may be made to patent application US201109043, which claims a process for synthesizing a tetradentate amido macrocyclic ligand (1), comprising:
(a) protecting one of the amine groups of o-phenylene diamine with a tert-butyloxy carbonyl group (BOC);
(b) reacting the product of step (a) with dimethyl malonyl chloride in the presence of triethylamine;
(c) reacting the product of step (b) with trifluoroacetic acid to remove the protecting BOC group; and
(d) reacting the product of step (c) with oxalyl chloride in the presence of triethylamine to produce a tetradentate amido macrocycle ligand (1).

Ligand (1) was further deprotonated using a strong base, n-butyllithium, and reacted with ferrous chloride in dry tetrahydrofuran and exposing the resulting mixture to air to obtain Fe complex (2). The synthesized Fe-complex in said patent is used as an activator of H2O2 in various oxidation chemistries.
References may be made to thesis titled ‘Coordination Complexes of New Acyclic and Macrocyclic Ligands’ by Horner, Stephen Thomas deals with the design and synthesis of a series of acyclic and macrocyclic ligands containing pyridine and amide groups. It is disclosed in the abstract the complexes of acyclic ligand designated H2LMe which and has methyl groups attached to the pendant pyridine groups. An anionic iron complex with two deprotonated ligands coordinated around the metal center is synthesized and structurally characterized as [Et4N][Fe(LMe)2]. A related tetraamide extended ligand with ferrocenyl groups is also disclosed which is synthesized by the reaction of Fe(CoCl) with H2O2. It is further disclosed that macrocycles are formed by double Michael addition of amines to the vinyl groups of ligand. In particular, reaction with n-butylamine gave the macrocycle H4LnBu, and reaction with ethylenediamine gave H4Len in high yield. Cobalt complexes of both these macrocycles and the acyclic precursor, H4LacrA, are also studied. The complex formed with the acyclic ligand contain two ligands coordinated to the cobalt center via the pendant rather than the headgroup amides, resulting in a square-planar coordination geometry around the cobalt center.
References may be made to an abstract in an article titled ‘Tetraamide macrocyclic complexes of transition metals with ligands derived from hydrazine’ by Mohammad Shakir, Khan S. Islam, Transition Metal Chemistry Volume 22, Number 2 (1997), 189-192 disclose succinic acid or phthalic acid reaction with hydrazine hydrate and formaldehyde in the presence of metal ions to give the macrocyclic complexes [ML1Cl2] or [ML2Cl2][M=FeII, CoII, NiII, CuII and ZnII]. The coordination of amide groups through nitrogen and the overall geometry of the complexes have been assigned on data obtained from elemental analyses and all the complexes exhibit an octahedral geometry, except copper which is square planar, where the amide group coordinates through nitrogen, and are air stable. [ML1Cl2] disclosed relates to dichloro(6,9,15,18-tetraone-1,2,4,5,10,11,13,14-octaazacyclooctadecane) metal (II); [ML2Cl2] is dichloro(6,9,15,18-tetraone-7,8,16,17 dibenzol1,2,4,5,10,11,13,14 octaazacyclooctadecane) metal (II) where M is Fe, Co, Ni, Zn.
TAML (tetraamido macrocyclic ligand) catalyst is very much effective in nanomolar to low micromolar concentrations in aqueous media with turnover frequencies thousands per minute that are similar to native peroxidases. The very high turnover number observed for this class of catalysts has been shown the robustness of the tetraamido macrocyclic ligand framework which makes these Fe(III) complexes resistant to oxidative degradation. They have been used to perform various oxidations in water using H2O2 and can be used for the degradation of various environmental pollutants. But the major problem of this catalyst is it loses activity below pH 4 due to acid catalyzed demetalation.
The stability and reactivity of Fe-TAML's are best controlled by modulating the σ-donor ability of the deprotonated amide nitrogen atoms in the 6-membered ring. Replacement of the —CMe2 by the corresponding electron withdrawing —CF2 in the malonyl fragment of the 6-membered ring shows very positive effects on acid stability and reaction rates. But fluorinated —CF2 unit in the catalyst framework renders its usage unsuitable for water treatment applications and is not eco-friendly.
Therefore optimizing environmental clash and developing low molecular weight protein free inorganic ‘Green catalyst’ that competes catalytically while showing robustness in extreme acidic and basic environment remains a challenge to the scientific community.
In the above context, the present inventor has sought to develop environmentally friendly macrocylic ligands and its metal complex that can lead to new generation of peroxidase mimics and function as oxidation catalyst. It is the object of the invention to provide metal complexes of oxidatively robust frameworks with selected macrocyclic rigid ligands, and to develop a simple high yielding process of preparation thereof, which have attributes better than the CF2 functionalized Fe-TAML.
Further, it has been shown that high-valent iron-oxo species are the key reactive intermediates in the catalytic dioxygen activation by heme and non-heme iron enzymes. These reactive intermediates either follow an oxygen atom transfer or electron transfer for the oxidation of myriads of substrates. Hence it has dragged a huge interest in designing both heme and non-heme iron complexes that would mimic the native enzymes where a high valent Fe-oxo species is achievable upon oxidation. A ligand system that is resistant to oxidation and helps stabilizing the high valent Fe-oxo species injecting more electron density is highly desired. FeIV-oxo species has already been synthesized and well characterized by spectroscopy and x-ray crystal structure [Jo'zsef Kaizer, Eric J. Klinker, Na Young Oh, Jan-Uwe Rohde, Woon Ju Song, Audria Stubna, Jinheung Kim, Eckard Mu{umlaut over ( )}nck, Wonwoo Nam, and Lawrence Que, Jr; J. Am. Chem. Soc. 2004, 126, 472.]. These species are stable at ambient temperature for a long time period and also able to oxidize unactivated C—H bonds like cyclohexane. However, a FeV-oxo species is believed to be more oxidizing in nature than FeIV-oxo species, and hence efforts have been made in making the same. In 2007 Collins and co-workers have trapped FeV-oxo species from [FeIII-TAML] that is only stable at −40° C. and used for the oxidation of organic sulfide to sulfoxide [Filipe Tiago de Oliveira, Arani Chanda, Deboshri Banerjee, Xiaopeng Shan, Sujit Mondal, Lawrence Que Jr., Emile L. Bondmar, Eckard Münck, Terrence J. Collins; Science, 315, 9, 835; Soumen Kundu, Jasper Van Kirk Thompson, Alexander D. Ryabov, and Terrence J. Collins; J. Am. Chem. Soc., 2011, 133 (46), 18546]. However organic transformations could not be achieved at this temperature without ease.